The invention relates to fuel injection systems for internal combustion engines, and more particularly to pressure regulators in fuel injection systems.
A typical fuel injection system includes a source of fuel, a fuel injector, a pump for pumping fuel from the source to the fuel injector, a return line from the fuel injector to the source, and a pressure regulator in the return line between the fuel injector and the source of fuel. The pressure regulator controls the fuel pressure at the fuel injector.
Prior fuel pressure regulators maintain a constant absolute pressure (system pressure) or a constant pressure difference relative to a reference pressure, such as atmospheric pressure or intake manifold absolute pressure.
In prior fuel pressure regulators, the fuel pressure is often too high in conditions of low ambient air pressure, and is often too low in conditions of high ambient air pressure, so that a proper air/fuel ratio is not maintained.
Attention is directed to the following U.S. patents which disclose pressure regulators:
______________________________________ Hamilton 3,752,175 August 14, 1973 Ludwig 4,204,561 May 27, 1980 Amey 4,164,237 August 14, 1979 Atkins 4,436,112 March 13, 1984 Fehrenbach 4,431,026 February 14, 1984 Brettschneider 4,395,986 August 2, 1983 Sasaki 4,370,102 January 25, 1983 Ciaccio 4,357,921 November 9, 1982 Fehrenbach 4,327,767 May 4, 1982 Ishida 4,300,510 November 17, 1981 Bellicardi 4,284,039 August 18, 1981 Benjamin 4,237,924 December 9, 1980 Ohumi 4,231,347 November 4, 1980 Rissi 4,203,465 May 20, 1980 Bauer 3,971,409 July 27, 1976 Weber 3,662,779 May 16, 1972 Fehrenbach 3,511,270 May 12, 1970 Baumann 3,405,730 October 15, 1968 Teston 3,106,219 October 8, 1963 Howard 3,048,185 August 7, 1962 Young 3,045,691 July 24, 1962 Lipkins 2,998,256 August 29, 1961 Elder 2,939,480 June 7, 1960 ______________________________________